Insulating paper for electric wires and cables



Jan. 4,1927.

J. R. LONG INSULATING PAPER FOR ELECTRIC WIRES AND CABLES Filed Dec. 14 1925 5A VEN TOR.

Patented Jan.'4, 1927.

. UNITED STATES JOHN R. LONG, 01 TARENTUM, PENNSYLVANIA.

INSULATING PAPER FOR ELECTRIC WIRES AND CABLES.

Application filed December The object which I have in View is the provision of an insulating paper which will lend itself to ready winding 'on the wire or cable in the winding machine and which 5 will form and retain a smooth, unchafed surface which will slip readily through theformer or die through which the wrapped cable must pass to insure its uniform diameter.

The standard practice is to employ for this, purpose rope paper which is wound in strips in a plurality of plies about the wire or cable, pressure being applied to make the winding taut and smooth. This rope paper is made of old manila rope, because the paper made from new manila fiber is usually re garded as too expensive for commercial use for this purpose. Paper made from old rope is usually found to be contaminated with foreign matter, such as grease, oil, metals, sand, salt, etc, that have been accumulated by the rope stock in its previous service. 'Ihiscontamination impairs the dielectric properties of the insulation and results in currentloss. It is not commercially possible under the present. ractice entirely to remove these impurities rom old rope stock, and the stock which is obtainable is becommg more and more adulterated. In fact the supply is very limited, and is growing more an expensive, and of poorer quality, each year.

As a substitute for rope paper I have SUC".

ccssfully employed spruce pulp of a high grade such as that made from Swedish spruce wood. The paper thus obtained is of a high insulating character, but the frictional means employed in the process of applying the paper to the cable tends to abrade the surface of the paper and to accumulate a certain amount of fuzz, or lint, thus giving the outer surface of the wrapped insulation a roughness which interferes with its passing through the former or die through which the cable is passed o insure a uniform external diameter of its paper covering. Thus while the spruce pulp paper provides a much cheaper, and in many ways a much superior insu ation than the-rope paper above referred to, because of its being a mechanically pure cellulose free from foreign matter, it presents this mechanical difficulty in producing an outer surface lacking in smoothness.

Attempts have been made to overcome the chafing. Paper for this purpose has been made of a mechanical mixture of certam 1 1925. Serial No. 72,001.

proportions of wood cellulose and manila rope, or of hemp orother vegetable fibers; but such paper has not been successful, as it does not overcome the tendency to abrasion, and the presence of the impurities in the rope fiber has an injurious effect on the dielectric qualities of the paper.

To overcome the faults in these forms of insulation, I have invented a new and improved type of insulating paper for the purposes referred to.

An embodiment of my invention is illustrated in the accompanying drawing,- in which Figure 1 is a perspective view showing a single phase conductor designated by the letter A with my improved insulating wrapping designated by letter B.

Fig. 2 illustrates an enlarged modified construction of the insulating wrapping shown in Fig. 1 before the same is wound around the conductor.

The same comprises a multiple-ply paper, the body 2 of the same being formed of cellular material, such as a good grade of spruce pulp, while-the outer surface 1, which is brought in contact with the wrapping and tension means of the wrapping machine, is formed of a layer of paper made of hemp or some other suitable vegetable fibre, such, for instance, as cotton, jute or ,flax, which is not subjectto abrasion and which forms a smooth, even, outer surface which will pass readily through the formers or dies of the wrapping machine. If desired, both sides of the paper may he provided with a layer of the manila hemp material designated by 1 and 3 as shown in Fig. 2, but I do not regard this as warranting the extra expense.

In making my improved paper I am able to use with success old rope as a stock material for the exterior layer of the paper, owing to the fact that the body of the paper being formed of wood cellulose, such impurities as may be carried in the rope-paper surface layer will be so isolated as to be pro-. 100 vented from causing any harm or in any impairing the dielectric properties of the wrapping.

In winding the paper insulation on wires and cables, especially in the case of high- 105 voltage cables, the paper is put under very considerable tension, and wood cellulose paper being of relatively shorter fibre is less able to stand up under the rough usage than is rope paper. The provlslon of the can mail

terial or other vegetable fibre lengthwise of the paper or in the direction of winding I obtain a still better result from the strength of the manila rope fibers.

lVhat I desire to claim is 1. An insulating paper for winding electric wires and cables, which is comprised of a body of mechanically pure wood cellulose material which has been freed from nonfibrous and resinous matter and a surface of vegetable fibers of the character described.

2. An insulating paper for winding electric wires and cables which is comprised of a body of mechanically pure wood cellulose material which has been freed from nonfibrous and resinous matter and a surface, which is exterior in winding, of vegetable fibers of the character described.

3. An insulating paper for winding electric wires and cables which is comprised of a body of mechanically pure wood cellulose material which has been freed from nonfibrous and resinous matter and a surface, which is exterior in winding, of vegetable fibers of the character described, the majority of the vegetable fibers being laid in the direction of tension in winding.

4. An insulating paper for winding electric'wires and cables, which is comprised of a body of mechanically pure wood cellulose material which has been freed from nonfibrous and resinous matter and a surface of manila hemp fiber.

5. An insulating paper for winding electric wires and cables, which is comprised of a body of mechanically pure wood cellulose material which has been freed from nonfibrous and resinous matter and a surface which is exterior in winding of manila hemp fiber.

6. An insulating paper for winding elec tric wires and cables, which is comprised of a body of mechanically pure wood cellulose material which has been freed from nonfibrous and resinous matter and a surface of vegetable fibers of the character described, the majority of the manila hemp fibers being laid in the direction of tension in winding.

7. An insulating paper for winding electric wires and cables, which is comprised of a body of mechanically pure wood cellulose material and a surface of manila rope paper.

8. An insulating paper for winding electric wires and cables, which is comprised of a body of mechanically pure wood cellulose material and a surface, which is exterior in winding of manila rope paper.

9. An insulating paper for winding electric wires and cables. which is comprised of a body of mechanically pure wood cellulose material and a surface of manila rope paper, the majority of the rope fibers being laid in the direction of tension in winding.

Signed at Tarentum, Pa, this 28th day of November 1925.

JOHN R. LONG. 

